> Einhllende des FRESNELschen Integrals C(xi):
> Y(xi):=1/2+A*exp(-B*xi)+C*exp(-D_*xi);  A:=0.45793743891023;
> B:=0.88290504747386;C:=0.10121459861159; D_:=0.11378765780382;        
>                                                       

             Y(xi) := 1/2 + A exp(-B xi) + C exp(-D_ xi)


                        A := 0.45793743891023


                        B := 0.88290504747386


                        C := 0.10121459861159


                        D_ := 0.11378765780382

> y(xi):=1/2+a*exp(-b*xi)+c*exp(-d*xi); a:=-0.40399067807815;
> b:=0.83757109631419; c:=-0.10355947371466; d:=0.11915836569374;

              y(xi) := 1/2 + a exp(-b xi) + c exp(-d xi)


                        a := -0.40399067807815


                        b := 0.83757109631419


                        c := -0.10355947371466


                        d := 0.11915836569374

> Y(xi):=1/2+A*exp(-B*xi)+C*exp(-D_*xi):
> y(xi):=1/2+a*exp(-b*xi)+c*exp(-d*xi):
> plot({1/2,Y(xi),y(xi),FresnelC(xi)},xi=0..10,numpoints=100,color=black
> );

> Y(infinity):=evalf(subs(xi=infinity,Y(xi)));

                     Y(infinity) := 0.5000000000

> y(infinity):=evalf(subs(xi=infinity,y(xi)));

                     y(infinity) := 0.5000000000

> C[infinity]:=Limit(FresnelC(xi),xi=infinity): % = value(%);

                       lim        FresnelC(xi) = 1/2
                  xi -> infinity

> 
